The aim of the present work was to improve the understanding of the impact of malignancy grade and myogenic/rhabdomyoblastic differentiation on the natural course of retroperitoneal liposarcoma. All consecutive patients affected by primary well-differentiated (WD)/dedifferentiated (DD) retroperitoneal liposarcoma, surgically treated at our institution between January 2002 and December 2011, were retrospectively evaluated. Tumors were stained for mdm2 and 5 myogenic markers (smooth muscle actin-α, h-caldesmon, calponin, desmin, myogenin). The French National Federation of the Centers for the Fight Against Cancer (FNCLCC) grading system was applied. Overall survival, crude cumulative incidence of local recurrence, and distant metastases were calculated. Multivariable analyses were carried out. A total of 144 patients were identified. Median follow-up was 68 months (interquartile range: 46 to 104 mo). Fifty-two patients were affected by WD/G1 and 92 by DD liposarcoma. Among the latter, 60 were grade G2 and 32 G3. Myogenic differentiation was present in 54 cases (8/52 WD/G1, 27/60 DD/G2, 18/32 DD/G3). Seven cases had a rhabdomyoblastic DD component (1/60 DD/G2 and 6/32 DD/G3). Five-year overall survival rates were 93%, 57%, and 21% for WD/G1 liposarcoma, G2 DD, and G3 DD liposarcoma, respectively, and 75%, 42%, and 29% for liposarcoma without myogenic differentiation, with myogenic differentiation, with rhabdomyoblastic differentiation, respectively (P<0.001). Of note, 5/6 patients affected by G3 DD liposarcoma with a rhabdomyoblastic component died within 8 months. FNCLCC grade and myogenic differentiation significantly predicted the outcome of retroperitoneal liposarcoma. These should be factored into treatment decision-making and possibly used to stratify patients in clinical trials.
本研究的目的在于进一步了解腹膜后脂肪肉瘤的恶性级别和肌源性/横纹肌母细胞分化对其自然病程的影响。我们回顾性研究了我们研究所在2002.1-2011.12期间的、外科手术切除的腹膜后原发性高分化（WD）脂肪肉瘤/去分化（DD）脂肪肉瘤病例。肿瘤经免疫组化mdm2和5个肌源性标记物(smooth muscle actin-α, h-caldesmon, calponin, desmin, myogenin)染色。应用法国国家抗癌中心联盟 (FNCLCC)分级标准。计算生存期、局灶复发以及远处转移的大概累积发病率。进行多变量分析。共计144例，中位随访时间68个月 (四分位数间距: 46-104个月)。52例为 高分化脂肪肉瘤/G1，92例为去分化脂肪肉瘤。后者中，60例G2和32例G3。54例有肌源性分化 (8/52 WD/G1, 27/60 DD/G2, 18/32 DD/G3)。7例为有横纹肌母成分的去分化脂肪肉瘤(1/60 DD/G2 和6/32 DD/G3)。5年生存率分别：WD/G1脂肪肉瘤为93%，G2 DD为57%，G3 DD脂肪肉瘤为21%；无肌源性分化脂肪肉瘤为75%，有肌源性分化脂肪肉瘤为42%，有横纹肌母细胞分化为29% (P<0.001)。值得注意的是，5/6的G3 有横纹肌母细胞成分去分化脂肪肉瘤病例在8个月内死亡。FNCLCC分级和肌源性分化对腹膜后脂肪肉瘤具有显著的预后意义。这二者应该成为腹膜后脂肪肉瘤治疗决策的因素，也为临床对患者分层提供可能。